Duplex repeater



W. J. HERDMAN DUPLEX REPEATER Original Filed Jul}. 10. 1920 2 Sheets-$hee1 X 1 70M; f0 m- Aug. 5 [1924. 1,503,650

W. J. HERDMAN' DUPLEX REPEIQ'I'ER ori inal r ned July 10. 1920 2 Sheets-Sheet 2' Federated Aug, 5, race.

WILLIAM J. HERDMAN, F TORONTO, DNTARIO, C.&NADA.

DUPLEX REPEATER.

'ii ncauo fiisciui 10,1920, Serial in. 395,251,

To all whom it may concern:

Be it known that I, WILLIAM J. HERD- MAN, a citizen of the America, and a resident of York, and Province of Ontar1o,Canada, have invented anew and usefulv Improvement in Duplex Repeaters, of which the following is a specification.

y invention relates to signal or voice current repeaters and pertains specifically to that clam of such devices which augment or amplify the currents received Without distorting the same.

e principal Y objects of my invention comprise, producing a repeater which is duplex in operation, in that it repeats in either of two directions with equal facility, a repeater that is self balancing or compen sating with regard to the length of lines or load connected thereto, and one that is extremely simple in construction, operation of Toronto, county and maintenance.

I accomplish these and other very desirable features which will hereinafter be pointed out and described, by means of a novel arran ement of apparatus and circuits wherc y incoming signals or voice currents from either direction may be detected by suitable receiving apparatus, and the amplified or augmented energy returned to the line conductors in such manner that the receiving device is not sensible thereto; even though the lines connected to the re peater are unbalanced with regard to length or load condition.

In the figures which accompany and form a: part of this specification, and in which spending parts throughout; 9 Fig. 1 illustrates diagrammatically the and magnetic receh 111 transmitting means. Fig. 2 illustrates diagrammatically a different method of connecting the line conductors to the circuits and apparatus shown m Fig. 1.

Fig. 3 illustrates diagrammatically the apparatus and circuits comprising a further embodiment of my invention, utilizing vacuum tubes as receiving and transmitting means.

Fig. 4 illustrates ther embodiment in diagram a still .fur of my invention and I shows a preferred United States of v Renewed December 26, 1923.

form of transformer for use with the same.

Referring now particularly to the arrangement shown in Fi 1, my invention comprises the transformers 1, 2, 3 and 4-, one winding of each, as 6, 7, 9 and 12 respectively, being connected in series to form the closed circuit; winding 6, conductor 16, winding 7, conductor 36, winding 9, c0ndoctor 17, winding 12 and conductor 35.

s ren stares.

reierably the windings so connected are those known as the semndary windings. Theremaining or primary windings 5 and 11 of transformers 1 and 4 respectively, are connected in series and through conductors 26 and 29 to binding posts 27 and 28 respectively, to which line conductors may be connected, likewise the remainin or primary windings 8 audit) of transtormers 2 and 3 respectively, are connected in series and through conductors 31 and 3G with the windings comprise the four arms of the bridge. The windings constituting the arms or the bridge are so related to each other with regard to resistance, reactance and turns that the product of the impedance of winding 7, multiplied by the impedance of winding 12 is exactly equal tothe prodnot of the impedance of winding 6 multiplied by the impedance of Winding 9 and thus the arrangement is in perfect balance when traversed by either direct or alternating current entering the bridge at the mid points of conductors 16 and 17. An electromagnet-ic receiving device 19, such as is common in the art, is connected by conductor 18 with the mid point of conductor 35 through conductor 22 with the mid point of conductor 3 The receiving ,device 19 is as shown functionally related to a microphonic transmitting device 20, also well known in the art, one terminal of h is connected through conductor 21, he mid point of conductor 16 and the other terminal of which is connected through conductor 23, battery 24 and con ductor 25 with the mid point of conductor 17.- In other words, the receiving device 19 is connected I to the bridge at points thereoi corrcswndinsg to the galvanometer I of the bridge correspondin I i connection in an ordinary ridge that is to connection in an ordinary bridge that is to say, to a pail-of conjugate points, while the transmitting device 20 is connected to 'polnts to. the battery say, to the other pair of conjugate points of the bridge. In practiw and preferably, the windings 6, 7, 12 and are made equal with'regard ,to turns. 'ghe windings (S and 7 are equal 1n resistance but of very much lower resistance than the resistance of the windings 12 and 9, which are likewise equal in resistance and the'closed circuit or bridge is, therefore very much unbalanced to ourwhy the arrows, will generate corresponding rent traversing it from the mid-point of conductor to the mid point of conductor 36. ,Thus if this arrangement of -circuits and apparatus be connected by binding posts 27, 28 and 32, 33 in a telephone line for example thevoice currents traversing windings 5 and 11 in the direction indicated voice currents in the windings 6 and'12 in the direction of the arrows shown near these windings and obviously, more current will 'fiow through the path, Winding '6, conductor 16, winding 7, conductor 22, receiving device 19 and conductor-18 than will flow through the path, winding 1 conductor 17 winding 9-, conductor 22, rceiving device 19 and conductor 18, because the former path is of very much lower resistance. Ob-

.viously, the currents flowing through conductor 22,"receiving device 19 and conductor-'18 will be in opposite directions, but the algebraic sum of these two currents will cause the receiving device 19 to operate the diaphragm of the transm1tting device20 and thus an augmented current of similar.

wave form. will be transmitted to the bridge arrangement through the mid points of conductors 16 and 17. This augmented current will divide at the mid points of con ductors 16 and-17 and part of this current "will flow through windings 6 and 12 and.

art of the current'will flow through windi'n'gs 7 and 9, and no'fiow of current nor any difference of potential will be manifested in receiving device 19, because the drop in potential along each of the two paths just indicated is equal. Thus no interference can result through regenerativeaction and the'augmented current will be inductively transmitted through-the transformers 1, 2, 3 and to the telephone lines connect-ed to the device.

It will further agaaae that if o it-- maries 5 and 11 the transformers 1 and.

2 have the same'nun'iher oi' turns and resist dance, and if the cores ot'.-these transformers are-equal in weightand character of iron,

tliatljan'y change ,in'the line connected to bin'dingpposts 27 and 28' with regard to r either length of 'line' or. loading of line will not'ca'hse' any. ;unbalancing of the local closed circuit or bridge because such change Krill affect the impedance of both winding (1 and winding 12 equally and the condition necessary for balance of the bridge, viz, I

impedance of 6 impedance of 9:

' impedance 7 Ximpedance of 12 will he maintained because [both sides of the above equation will have been equally modified, through the equal modificat on of an element in each side of the equation. This is of course equally true oflines connected to binding posts 32 and 33,; therefore the arrangement is automatically self balancing or selfcompensating where long or short lines' are connected thereto or where combinations of long or short lines {or unequally loaded lines are connected thereto.

of my invention, employing vacuum tubes or electron discharge devices for the reception and transmission of signals or volce currents. In this arrangement, because the three element vacuum tube or audion is primarily a potential detector, the transformers 10 and 12 are provided with secondaries 16 and 19' respectively, having a i great many more turns thereon than their associated primaries 15 and'20. The sec? and 22 and theprimaries 15' and 17 and20 and 22 are uniform with regard to turns and resistance. It will thus be no that as before, the closed circuit; win ing 16,

conductor 23, winding 19, conductor 66,

winding 21, conductor 24, windin 18 and conductor 6:")

bridge in which the arms are the secondaries of the transformers 10, 11, 12 and 14,-

and in which incomin signals or voi e currents" generate much higher potentials in the windings 16 and 19 than in the win din'gs 18 and 21. There is thus a very apconstitutes a W ieatstoney m- .ondaries 18 and 21 have the same number of turns their associated primaries 17 preciabledifference of potential available I ,for impression from the mid point of conductor 65 through conductor 25 to the grid- 28 of the detecting audion 26, the filament. of which is connccted'tlirough eondu'etor32 with the mid point of conductor 66 to complete the detecting circuit of the audion. A- battery 31 is provided to illuminate the filament-27 ofthe audion 2'6 and the plate 29, is connected as shown to a terminal of formers are utilized and in 16 end 18 shown I 72 contains many more turns them the ondery-VYB or than one winding of the intor-yalve transformer 30, the other terminal of which is connected to the filament 27. The remaining winding of the inter-velve transformer is connected by one terminel throu h condenser 33, which is bridged e gri leek resistence 34, to the grid 37 of the amplifying eudion 3i}, and the other terminal of the winding is connected to the filament 36 of eudion 35, the plate 38 of which is connected through conductor 42 to the mid point of conductor 23. The filament-36 is illumihated by battery 39 and is connected to the plate battery 30, the positive terminal of which is connected through conductor 41 to the mid point of conductor 24. Such interconnection of audions is common 111 the art and it is thought theneny-description oi the action of the audions is unnecessary.

It will be sufiicient to soy that'the amplified and undistorted currents emanatingfrom the output circuit of the audion 35 will as heretofore described d1- vide at the mid points of conductors 23 and 24 and a portion of the current will traverse the secondaries 16 and 18, while the other portion of the current will traverse secondaries 19 and 21 to generate currents in their respectively associated primaries to thus impress the augmented current on the line conductors connected to the device at the binding posts 44, 45 and 48, 49. Further, if, as heretofore explained, the'product of the impedance of winding 16 multiplied by the impedance of winding 21 is uu-l to the product of the impedance of win ing 19 multiplied bythe impedance of winding 18, there will exist no dilference of potential at the mid points of conductors and 66 and the detecting audion 26 will therefore not be sensible to the amplified currents and hence no oscillation or regenerative action of the system of audions can result. Further, as the impedance of each vpair of primaries connected to the lines is equal, any change in the impedance of their associate pair oi secondaries due to difference of length of line or loading condition of line cannot result in unbalancing the closed circuit or bridge as heretofore explained.

Fig. 4 illustrates a preferred embodiment of. my invention in which but two transwhich the primaries 71 and 74 are-both wound in the same direction upon the core and are connected in series as shown. These primaries correspond to the primaries 15 and 17 of Fig. 3. The secondaries 72 and 73 are likewise wound in the same direction upon core 70 and correspond to the secondaries 1n Eig. 3. The secondary two'primeries 71, end l n p gectioe, I pro and 86. In this the total turnsof the.

for to make the total turns of the primaries 71 and 74 equal to the turns in the secondary 73, while the secondary 74 has from fifty to one hundred times more turns than the'secondary 73 or the two primaries 71 and 74 combined and preferably windings 71 and 742 are wound in one continuous winding of uniform length with the core, while the two secondaries are wound separately, superposed; in each other and likewise of uniform length with the core. Similarly, the primaries 81 and 84 are wound on core 80, While the secondaries 82 and 83 are like wise wound on the same core and connected as shown to complete the system. The terminals of primaries 71 and 74 are connected as shown to binding posts and 76,

While the terminals of primaries 81 and 84 are likewise connected to binding posts 85 embodiment the audion 100 constitutes the re eating relay, and the grid 104 is connected t rough conductor 102 with the mid point of the conductor connecting secondaries 72 and 7 3. The filament 103 is illuminated by battery 106 and is connected. through conductor 109 and condenser 108 with the mid point of conductor connecti-n secondaries 82. and 83. The plate 105 is connected through conductor 101 with the mid point of conductor 23 while the filament is connected through conductor 110 and plate battery 107 with the mid point of conductor 2 1. From the previous descriptions, it will be obvious thgit the audion 100 constitutes a repating relay, the input circuit of which is connected to the Wheatstone bridge at the points of zero otential thereof, while the output circuit 0 the audion is connected to the bridge at the points of energy input thereof and that therefore, the operation of the s stem is the same as that-hitherto describe From the foregoing, it will be obvious that have produced a si al or voice current repeater that is capa 1e of duplex,loperation in that it will transmit with equal facility in either of two directions without interference; that my device is automatically self compensating or balancing with regard to the lengths or load conditions of the lines to which it is attached and that further my device is extremely simple and Patents is as follows I adapted to receive electrical energy in unequal quantities respectively from said line circuit, a conductor common to said two local circuits and in which conductor the electrical energy in one circuit opposes the electrical energy in the other circuit, a detector in said common conductor and responsiv to the surplus of electrical energy in one locml circuit over the electrical energy inthe other local circuit, an output source controlled by said .detector, a local circuit for said output source; and a second line circuit associated with said last mentioned local-circuit and adapted to carry outputenergy.

2; In a duplex repeater two line circuits to carry input and output energy, two local circuits adapted to receive electrical energy in unequal quantities respectively from mitting circuits conduct ively connected to either of said line circuits, each of said line circuits giving energy to both ;of said local circuits, a conductor common to said two local circuits and in which conductor the electrical energy in one circuit opposes the eletrical energy in the other circuit, a detector in said common conductor and re sponsive to thesurplus electrical energy in one local circuit over the electrical energy in the other local circuit, an output source controlled by said detector, a local circuit system for said output source, said local circuit system local circuits to deliver energy to them, and

- said line circuits associated with said local 3a a circuit system.

3. In a signal repeater, an incoming line, an outgoing line, two local receiving circuits associated inductively with said incoming line in such mannerthat the two receiving circuits receive different quantities of energy from said line, two local transmitting circuits associated inductively with said lines, a detector, a] sourceof electrical energy, said receiving circuits acting differentially upon said detector, said source acting to impress equal potentials upon said transmitting, ircuits,'said detector and said source being associated to form a repeating relay for alternating currents, and each of said two transmit ing:circuits having parts in common with both of said two receiving circuits. J. Y

.4. In a signal repeater, two' local receiving circuits, a detector common to said two circuits, upon which said receiving'circuits act in. opposing .manner so that the said detector responds to the algebraic sum of thefenergy' in said'two receivingcircuits, two local transmitting circuits, aisource of energy common to said two transmitting circuits to which saidv source delivers equal potential at any instant, said two trans-- said detector circuits by reason of common paths insuch manner that said detector is associated with said two 5. In a duplex repeater, a Viheatstone bridge the arms of which are composed of impedances so related that while the bridge is in a state of balance, the arms associated with one pair of the conjugate points thereof are of unequal impedance, signal receiving means associated with a pair ct conjugate points of said bridge, signal transmitting means coii'unctionally related to said signal receiving means-and asso ciated with the other pair of conjugate points of said bridge, and transmission lines inductively associated with the impedances forming the arms of said bridge.

6. A duplex repeater comprising, a pluralit-y of impedances, a i/l' hea-tsbone'bridge the arms of which are composed of said impedances so related that while said bridge is balanced, the arms adjacent each of a pair of conjugate points of the bridge are of unequal'impedance, signal receiving 0 means associated with a pair of'conjugate points of saidv bridge, signal transmitting means co'functionally relatedto said signal receiving means and likewise associated with the remaining pair of conjugate points of said bridge, and transmission lines associated with the impedances forming the arms of said bridge.

7. In a duplex repeater,.a plurality of transformers, transformers being interoogmected to form a Whcatstone bridge, the impedance of said windings being so related that while the bridge is in a state of balance, the'windin'gsassociated with one pair of the conjugate points thereof are of unequal impedance, a repeating relay, the input circuit of said relay being associated with one pair of the conjugate points of said loridge,-the' output circuit of said relay being associated Witlh the other pair of conjugate points of said bridge, and transmission line conductors connected to the remaining windings ofsaid transformers.

8. In a duplex repeat/er, a plurality of transformers, corresponding windings of each of said transformers being connected to form a balanced Wheatstone bridge, the windings associated with one pair of the conjugate points thereof being unequal in impedance, a repeating relay; T the input circuit of which is connected to one pair of the conjugate points of said bridge and the. output circuitof which is connected to said bridge at the other pair of conjugate points thereof, and transmission lines c-onncciedd to the remaining windings of said trans 4 r iUllllclb. i

9. in a duplex repeater, a. pluralityiot impedances, said inip'edances Ming inter- 3% similar windings of said 109 1,,50s,e50 I m connected to form a, balanced atsbone of conjugate p bridge, the impedances adjacent each of a fiansmlssion line air 0f cmnjugate poinfis of wd bridge, impedances for ing unequal in im dance, wregeatiyg 1 i5 relay, the input circuit of said why beim with one pair of conjugate Witnesses: of d bridge, the m m circuit 0 said. E. mLAw, why being w: wifia tbs other pain M. 

